There are numerous devices and pieces of equipment which are intermittently operated and only require small amounts of oil at a time at a plurality of locations. Naturally, it is imperative that the delivery system be as reliable and as accurate as possible. Many of the prior art systems for delivering fluids in relatively large quantities use pumps and valves. However, on large pieces of equipment where the lubricating fluid has to be transmitted over large distances in small quantities, the prior art systems using pumps and throttle valves are unsatisfactory. If only small amounts at a time of lubricating liquid are required, costly systems using pumps and valve are required to provide in an automatic and continuous fashion such a minute and accurately measured quantity. Valves for such small quantities of oil usually leak, suffer from capillary action problems, or have other reliability problems that make then inadequate. Furthermore, prior art devices are generally not able to provide small, metered quantities of different grades of lubricating liquids at the same time.
There are a number of prior art systems which use dippers for transferring a liquid from a reservoir to a distribution system. Naturally, those prior art dipper systems which throw off a lubricant to surrounding parts cannot be used for transferring the lubricant large distances to a plurality of locations. Lubricators which use a throwing action are disclosed in U.S. Pat. No. 1,665,451 to Gates; Bartlett U.S. Pat. No. 1,771,835; Fehr U.S. Pat. No. 546,659; and Kraut U.S. Pat. No. 1,416,840. Each of the devices in the aforementioned patents requires that the rotating parts turn fast enough so that the oil will not drip back off those parts into the reservoir. On the other hand, if the rotating parts of these devices rotate very slowly, the oil which is picked up would drip back off these parts and no lubrication would be transferred.
The U.S. Pat. No. 1,288,765 to Ulferts, on the other hand discloses the continuous transfer of one drop of lubrication at a time; and should the transfer wheel 5 rotate too slowly, the droplets would constantly drop from the transfer tube 15 without being picked up.
Other prior art U.S. patents, such as Stickney U.S. Pat. No. 1,200,149; Fitzgerald U.S. Pat. No. 2,903,995; and Harper U.S. Pat. No. 1,929,243 disclose the use of dippers rotated into a reservoir of a liquid for picking up some of the liquid and thence to a delivery point. The Fitzgerald and Harper patents disclose the use of containers on the end of the dipper and hence transfer a greater quantity of oil than merely one drop. The Stickney patent on the other hand, discloses a plurality of dippers pivotably mounted onto a shaft which in turn is rigidly mounted onto a rotating disc. This system suffers from the disadvantages that the swingably mounted dippers may splash lubricant when being immersed therein and when emerging therefrom. In addition, the amount of lubricant being delivered cannot be precisely metered since the entire length of the dipper is wiped by the wipers.
None of the known prior art devices are capable of transferring a small amount of fluid at a time and delivering said small amount to a location spaced a relatively large distance from the reservoir of the fluid.